[Bug c/83703] Loop termination condition ignored in -O3, works in -O2 or with smaller values

[freddie_chopin at op dot pl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83703

--- Comment #4 from Freddie Chopin <freddie_chopin at op dot pl> ---
Would it be possible to have a warning with -Wall -Wextra when something like
that happens? I think this behaviour here is really strange and really
unexpected. In "real" programs I guess there are tons of such tiny undefined
behaviours so eliminating them is probably very hard, which would then render
-O3 option completely useless.